This invention relates to chilling and shrinking workpieces being conveyed to a workstation on an assembly Often it is desirable to chill and shrink workpieces in order to fit or press them into a larger assembly. For example, valve seats, valve guides or cylinder liners need to be chilled so that they can be fit or pressed into the block of an internal combustion engine.
Various means of cooling or chilling workpieces have been proposed For example, Ross U.S. Pat. No. 2,218,722 discloses a workpiece chilling device for use on an assembly line. The device has a chilling tray which comprises a lower compartment containing a chilling agent such as temperature controlling liquid air and an upper compartment containing a light fluid oil into which workpieces are immersed for chilling.
Colestock U.S. Pat. No. 3,621,550 discloses a refrigeration chamber to chill valve seats that are stored in a vertical magazine. The valve seats are chilled in a refrigerator chamber, and the chilled valve seats are transferred from the bottom of the magazine (by a pneumatic cylinder) to an assembly station.
Emerich U.S. Pat. No. 1,980,156 discloses means for making an expansion fit using carbon dioxide to shrink bushings. The carbon dioxide is led into the cooling chamber through a pipe.
Allen et al. U.S. Pat. No. 1,955,728 discloses a method and tool for inserting bushing in, or removing it from outer member by spraying the bushing with CO.sub.2 and a low-freezing point liquid.
Hofmann U.S. Pat. No. 4,713,942 discloses a method for cooling an object by contact with superfluid helium (He II) with a forced flow of He II to remove heat from the object
McCandles U.S. Pat. No. 2,487,821 discloses a method of cooling a metal object by advancing the object through a chamber having a thermally conductive wall. The outside of the chamber is cooled with a cooling liquid medium, and the object inside the chamber is further cooled by flowing a portion of the vaporing cooling medium into the chamber in a counter direction relative to the direction of advance of the object.
De Brosse U.S. Pat. No. 3,025,680 discloses a cooling system that uses liquid nitrogen for cooling certain electronic apparatus. Liquid coolant circulates in a closed
Stearns U.S. Pat. No. 3,972,202 discloses an apparatus for delivering cryogenic liquid to a heat exchanger where the cryogenic liquid is vaporized to effect cooling.
Stearns U.S. Pat. No. 4,715,187 discloses a system for delivering a controlled stream of liquid cryogen from a bath to an outlet and means to maintain cryogen in liquid phase as it flows through the conduit.